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3 years ago

Josie sees lightning off in the distance. A few seconds later she hears thunder. What can Josie conclude?

Chemistry

2 answers:

PilotLPTM [1.2K]3 years ago

6 0

Light waves travel faster than sound waves

Marat540 [252]3 years ago

6 0

Light waves travel faster than sound waves.

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A civil engineering student is considering buying an electric car. However, the conscious student wants to make sure her carbon

svetlana [45]

Answer:

$\text{An gasoline-powered vehicle has }\\\boxed{\text{five times the carbon footprint}}\text{ of an electric vehicle.}$

Explanation:

1. Miles travelled in an average month

$\text{Miles} = \text{1 mo} \times \dfrac{\text{52 wk}}{\text{12 mo}} \times \dfrac{\text{5 da}}{\text{1 wk}} \times \dfrac{\text{16 mi}}{\text{1 da}} = \text{347 mi}$

2. Using a gasoline powered vehicle

(a) Moles of heptane used

$n = \text{347 mi} \times \dfrac{\text{1 gal}}{\text{36.5 mi}}\times \dfrac{\text{3.785 L}}{\text{1 gal}} \times \dfrac{\text{679.5 g}}{\text{1L}} \times \dfrac{ \text{1 mol}}{\text{100.20 g}}= \text{244 mol}$

(b) Equation for combustion

C₇H₁₆ + O₂ ⟶ 7CO₂ + 8H₂O

(c) Moles of CO₂ formed

$n = \text{244 mol heptane} \times \dfrac{\text{7 mol CO$_{2}$}}{\text{1 mol heptane}} = \text{1710 mol CO$_{2}$}$

(d) Volume of CO₂ formed

At 20 °C and 1 atm, the molar volume of a gas is 24.0 L.

$V = \text{1710 mol } \times \dfrac{\text{24.0 L}}{\text{1 mol}} \times \dfrac{\text{1 gal}}{\text{3.785 L}} = \textbf{10 800 gal}$

3. Using an electric vehicle

(a) Theoretical energy used

$\text{Theor. Energy} = \text{347 mi} \times \dfrac{\text{1 kWh}}{\text{5.2 mi}} = \text{66.7 kWh theor.}$

(b) Actual energy used

The power station is only 85 % efficient.

$\text{Actual energy used} = \text{66.7 kWh theor.} \times \dfrac{\text{100 kWh actual}}{\text{ 85 kWh theor.}}\times \dfrac{\text{3600 kJ}}{\text{1 kWh}}\\\\ = 2.82\times 10^{5} \text{ kJ}\$

(c) Combustion of CH₄

CH₄ + 2O₂ ⟶ CO₂ +2 H₂O

(d) Equivalent volume of CO₂

The heat of combustion of methane is -802.3 kJ·mol⁻¹

$V= 2.82\times 10^{5}\text{ kJ} \times \dfrac{\text{1 mol methane}}{\text{802.3 kJ}} \times \dfrac{\text{1 mol CO$_{2}$} }{\text{1 mol methane}} \times \dfrac{ \text{24.0 L}}{ \text{1 mol CO$_{2}$}}\\\\ \times \dfrac{\text{1 gal}}{\text{3.875 L}} = \textbf{2180 gal}$

4. Comparison

$\dfrac{V_{\text{gasoline}}}{V_{\text{electric}}} = \dfrac{10800}{2180} = 5.0\\\\ \text{An gasoline-powered vehicle has }\\ \boxed{\textbf{ five times the carbon footprint}}\text{ of an electric vehicle.}$

6 0

3 years ago

explain how one and two letters chemical symbols are used to identify elements whose names begin with the same letter, for examp

Nadusha1986 [10]

The symbol of helium is He and this distinguishes it from the symbol for hydrogen.

<h3>What are chemical symbols?</h3>

Chemical symbol are the means by which we designate elements on paper. The symbols could be one letter or two letter as the case may be. There is no chemical symbol that has more than two letters that are used to designate the element.

We know that hydrogen has the symbol H. There is to way that another element will also have the symbol H as that would be tantamount to confusion. As a result of that, the symbol of helium is He and this distinguishes it from the symbol for hydrogen.

Learn kore about chemical symbol:brainly.com/question/9249660

#SPJ1

8 0

1 year ago

Which of the following is the best piece of laboratory glassware for preparing 500.0 mL of an aqueous solution of a solid?

Leni [432]

Answer:

The correct answer is option A.

Explanation:

Volumetric flask : A glass ware with round lower body with flat bottom and with thin cylindrical neck along with mark which indicates the specific volume filled to that mark.It is used in preparation of standard solution of compound with desired concentration with fixed volume.

Erlenmeyer flask : is a flask with conical shape with flat bottom used in titration experiments to carry out reaction with fixed volume of solution.

Test tube : Small cylindrical tube with rounded bottom used to observe reaction in between reactant taken in small amount.

Graduated beaker : Laboratory glassware used measure larger volumes of solution or to mix or stir solutions and liquids.

Graduated cylinder : Laboratory thin cylindrical glassware with accurate marking of volume used to measure an accurate volume of solutions or liquids required in an experiment.

<em><u>Volumetric flask</u></em> is the best piece of laboratory glassware for preparing 500.0 mL of an aqueous solution of a solid

8 0

2 years ago

Read 2 more answers

How much heat is required to vaporize 25g of water at 100*c

ElenaW [278]

Answer:

Heat required = 13,325 calories or 55.75 KJ.

Explanation:

To convert a water to steam at 100 degree celsius to vapor, we have to give latent heat of vaporization to water

Which equals ,

Q = mL,

Where, m is the mass of water present

L = specific latent heat of vaporization

Here , m= 25 gram

L equals to 533 calories (or 2230 Joules)

So, Q = 25×533 = 13,325 Calories

Or , Q = 55,750 Joules = 55.75 KJ

so, Heat required = 13,325 calories or 55.75 KJ.

4 0

3 years ago

50 POINTS!!!!!!!

KATRIN_1 [288]

We could reduce soil erosion and recycle phosphorus from farm and human waste so that we could help make food production sustainable and prevent algae blooms. We can also do land reclamation as well to help solve this problem. With the land, we would have to design a system to where the land could be functional again in order to plant crops, trees, also to help the wildlife that was once a part of the island. Therefore if the design is done before the mining then afterward we can do the reclamation of the land which would help the people to be able to function after the mining. It would also help the future generations that come along after the previous generations. Everyone must work together in the process in order for everyone to survive. If all this is done then the people of the island would not have to import their food. The reclamation process is the most important thing that has to be designed first whether it is land, soil, water, lakes, and clay then after plant trees, vegetation, and other forms of plants to help replenish the land after the mining is done.

I hope I helped :3

7 0

2 years ago